Polymarket price data
Polymarket price data: 1-minute for free, 250ms with the book
Polymarket's own prices-history endpoint is free, keyless, and reaches back to market creation, but its floor is [1 minute](/polymarket-price-history). When a study needs prices aligned with depth — mid, spread, and VWAP on the same timestamp — the archive serves all three on a 250ms grid.
Figures measured as of 2026-10-02 on the published PolyOrderbooks archive.
Short answer
The free floor, and the aligned offer
For charts and implied probabilities, Polymarket's /prices-history is enough and it is free: per-token price series back to market creation at 1-minute buckets, no key required, and measurably still working on long-resolved markets when the request is bounded with startTs and endTs.
When prices must line up with depth — a backtest fill, a spread study, a liquidity regression — 1-minute buckets and unaligned sources are the limitation. The archive serves prices as the midpoint at each 250ms snapshot, so price, book, and metric all answer the same moment.
Under the hood
What each source gives
Why it matters
Mid, spread, and VWAP on one timestamp
The prices endpoint returns the midpoint — the average of best bid and best ask — at each timestamp, and metrics add spread, depth, and VWAP computed from the same L2 data. Everything joins in one DataFrame because everything shares the capture moment.
For spread work, the 60-second resampling recommendation still applies: at 250ms, single captures can show transient quote noise that a 60-second series smooths away.
Get it
Where to get it
- Official prices-history — free, 1-minute buckets, full history; bound with startTs and endTs (price history guide).
- Archive prices — 250ms mid aligned with books and metrics over REST; free Starter with 3 days.
- Download options — CSV/JSON sample and research datasets (datasets).
- Know the limit — the price-history 0-points edge case on unbounded requests is documented and measured (API pricing).
FAQ
Is Polymarket price data free?
Yes. The official /prices-history endpoint serves per-token price series back to market creation at 1-minute buckets with no key, and it keeps serving fine granularity on resolved markets when the request is bounded with startTs and endTs.
What resolution does Polymarket price history support?
One minute is the floor; the fidelity parameter is expressed in minutes and 1 is the minimum. Anything finer — 250ms prices aligned to the book — has to be captured, which is what the PolyOrderbooks archive does.
How are archive prices calculated?
Each price point is the midpoint of best bid and best ask at that snapshot, aligned 1:1 with the stored book. Metrics add spread, total bid/ask depth, and VWAP on the same timestamps.
When is official price data enough?
For simple charts and implied probabilities, yes. Use archived data when prices must match depth — backtest fills, spread analysis, or liquidity measurements — because filling at mid or last trade flatters results on books that are one-sided 16.9% of the time.